Information sheet on dehydrated white or Irish potatoes

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INFORIIATIOn SHEET CN DEKYDRA.TED '"FITE OR IRISH POTA'

The Dehydration CorjnittBe
Bureau of Ac^'icultural CYierdszry £;nd Enf,lnef;ri
U» S. Depar tine Tit ci' Agriculture

Potatoes sre dehydrated in the fona of slices (Lyonnaise), cube

(scalloped), strips (French fried), and riced (r.ashed), prior to .drying,
the first three types are partially cocked or "blanched." It is neces-
se.ry that thc-y be rehydrated by soaking in v/£;t:er before using. After
rehydration,, the potatoes can be cooked in the sc-jne avay as e:re fresh
potatoes, soinev/hat less cookinf, time being req^jired. The ric .:d" t;;,rpe is
pr:-ct:ical ly conpletely cooked and needs only a short sot.king in hot water
before use.

The dehydrated products nust b'. prepared under nooorn sanitary condi-
tions, in accordance vath best coinriercif.'l practice and Federal and State
Pur*^ Food Lavv's rnd Regulations .

VAJriEriES:

W

Preference is given to varieties that are meoly after cocking by

boiling. Potatoes thxt are dark colored or soggy after cooking should
not be used. The Idaho Russet typ's are satisfy. ctory. Oregon Gems,
Klr^inath Russets and. Burba nks are also good. Satisfactory products have been
made frcn. Irish Cobbler, Early OhiOjChippeiva and Bliss Triumph ^^arieties.

It is not possible to state definitely tliat tny variety v.-ill or
vill net be satisfactory v/-hen gro-A-n lander varying conditions. Anyt^-pe
or variety -.vhich-TieetG the above conditions may be used for dehydration,

PREPARATIOr:

Only clean sound potatoes should be used for dehydration. The
pctctoes must be thoroughly vrashed so th.at r.ll dirt is removed. Yihen
abrasive peelers are used, tubers should be sized, othervdse excessive
losses TCi-j>y ensue. Irrrr-^j.lar shape- should be avoided, if v/astago is to
be kept to a minimiom. All potatoes dr.rken to some extent after peeling;
some varieties darken rapidly, others slowly, and some mf?y turn red.
These discolorations c^n be prevente'i by inmedit.tely placing the peeled
tubers in cold runi"iing water or in a dilute salt solution (1 to 2%).
After peeling, the eyes vjnd f ny discolored spots must be trimmed out.
Any spots left v.-ili shov; up in the r-.hydrated m.atorial and may result
in rejection of the v/hcle lot. Care in peeling, rnd trimming vrili cut
down- the v.^stage to no .small degree.

The potatoes should bo cut r* s follov.'s: slices, from 3/l6" to
4/16" thick; cubes, from 3/l6" to 6/l6". on a side; strips, noS; less
than 3/4" in length and in cross-section, not less than 3/l6" and not

2 - Infoi-nation Sheei: on Dehydrated ■•vhito cr Irish Potatoes

more than S/lo". preferably the cut potatoes should be placed direct-
ly on the trayp or belt on vrhich they are to be blanched. Innediately
after cutting the^pieces should be washed thoroughly by stronr sprays
of cold clean v;ater in order to remove starch from the cut surfaces.
If not blanchied imrr^.ediately the cut material must bo kept under running
cold v.^ter or in a clean 1 to 'l^o salt solution. In no case shall the
material be so helc for more then one hour,

PEELING AND TRILH-GNG LOSS;

Waste v.lll run f3X)m 17 tc 25.^.

BLANCHING;-

The piece-s are blanched in flov.lng steam at not less than 190° F.
until translucent, usually about 3 minutes. Care must be taken th^,.t
the steam reaches all pieces; in crder to prevent "case-hardeninj.: ."
Case-hardening is f conditioii v/hich develops when dehydration is attempt-
ed at too high a temperature and too lov/ relative humidity. It consists
of the formaticn of a iiorny shell v;hich slov/s up both dehydrritior; and
rehydration. Water blanching or "series" blanching in v/ater results in
greater idtrmin losses then v/hcre steam is used.

TRAYING:

There should be a mj.nirium of overlapping on the drying surface.
If, hcv/cver, the slicing and spraying hc\'-e been carefully done, trouble
from sticking, vd 11 not be too great. Too hea\y loading vdll increase
the drying time. Strips ore usually loe.ded l-l/4„lbs. to the 'square
foot; slices 3/4 to 1 lb.; dice up to 1 to l-l/i lbs.

DRYING TEl^PFRATURES :

Finishing tem.peratures should not exceed 150" F.

MOISTURE CONTEMT:

The moisture content of dehydra.ted potato strip;^, slices cr
cubes must not exceed 6^ ivhen packed ready for shipm.ent.

YIELD: ■ • ■

The yield vdll be from 15 tc \1% based on the weight of the fresh
unprepared product.

VTTAI'IN CONTENT:

V\/hen properly prepared, th'.^ freohly dried product 'vill contain
approximately 425 micrograms of vitf^min B]_ (thit:o:iin), 250 mAcrcgrams

i

- I nf c nra t*ic n. Sheet on Dehydrated li^Tiite or Irish Pctr.toes

cf vitrmin Bo (ribcflc.vin.), and 25 nillir-rtms cf vitrnin C (ascorbic
acid) per 100 f:r?:r.s. No ^rrantee cf Titojnin coTitent cf the products
should be given.

PRECOOKED POTATOSG (HICSD);

The chief difference betv-'een this snc the ether types cf dehydr^'.tod
pct&tces lies in the fact that this fom is precooked before drying.
After washing', the tubers are peeled and thcrou-rrhly precooked. Ivhen
soft, they are passed thrcurh the ricing device and the strin;;£ dropped
directly onto the treys. If ricod v/hile hot, the strings do not have
such a tendency tc; stick together or to the tr^ys. The strings should
net be over l/8 inch in diairieter. Drying is similar tc the ether forns
but is acccnplished in a much shor'cer tine.

The ncisture content cf the finished product raust not exceed 7%
v/hen packed ready for shipnent.

Detailed specifications covering purchases are issued by the Office
of the Quartermaster General of tlie U.S. iijrviy ajid by the Agi'i cultural
Marketing Adninistrction in Washington, D. C.

If further detailed information is aesirod, inquiries should be
addressed to

The Dehydration Corcnittee

Bureau of Agricultu.ral Chei.-iistry and Engineering

U.S. Depar«fcmcnt of Agriculture

IVa sh i ng t on , D . C .

or tc

The Dehjrdration Coririittee

Eurecu of Agricultur-^ 1 Chemistry rnd Engineering

U.S. Department cf Agriculture

800 Buchanan Street

Albany, California..